Switched PSM to popover on smaller screens

refs https://github.com/TryGhost/Team/issues/840

- first pass at CSS-only PSM popover behaviour on screens <1024px

ghost/admin/app/styles/components/settings-menu.css

@@ -394,6 +394,19 @@
     min-width: 501px;
 }
 
+@media (max-width: 1024px) {
+    .settings-menu-container-labs {
+        position: absolute;
+        right: 0;
+    }
+}
+
+@media (max-width: 800px) {
+    .settings-menu-container-labs {
+        padding-bottom: 64px;
+    }
+}
+
 .settings-menu-toggle-labs {
     position: absolute;
     top: 31px;
@@ -473,4 +486,4 @@
 
 .gh-publishmenu-labs {
     margin-right: 8px;
-}
+}

ghost/admin/app/styles/layouts/editor.css

@@ -297,6 +297,12 @@
     max-width: calc(100vw - var(--editor-sidebar-width))
 }
 
+@media (max-width: 1024px) {
+    .gh-editor {
+        max-width: 100%;
+    }
+}
+
 .gh-editor-header {
     position: absolute;
     top: 0;